Australian Antarctic Division: Leading Australia’s Antarctic Program

The sound of krill

Antarctic scientists hope an experiment to capture the ‘sound’ of a single krill will help determine how many of the Antarctic keystone species are swimming around in the Southern Ocean.

Researchers at the Australian Antarctic Division are using echo sounding technology to record the sound of different sized krill across a range of frequencies.

Australian Antarctic Division acoustician, Dr Martin Cox, said if scientists can match frequency signals to an individual krill, they will be able to determine the number of krill in an entire swarm in the wild.

“The echo sounders transmit pulses of acoustic energy into the water. When they hit an object, such as krill, the energy is reflected back, amplified and illustrated on a digital display,” Dr Cox said.

“When we’re using an echo sounder to observe a krill swarm from a ship in the Southern Ocean, we want to be able to interpret these signals and determine how many krill make up the swarm,” Dr Cox said.

The distance of the krill from the echo sounder is also a factor, so the experiment will use underwater cameras to monitor the exact position of each krill as its sound is recorded.

Dr Cox said the data from the experiment will also allow scientists to interpret information collected by krill fishing vessels.

“There are a lot of fishing boats using advanced echo sounders which work on a different frequency to the ones we use, so we don’t have data on how krill reflect sound on those frequencies.”

Commercial krill fishing in the Southern Ocean is regulated by the Commission for the Conservation for Antarctic Marine Living Resources (CCAMLR).

Australia’s Scientific Representative to CCAMLR, Dr Dirk Welsford, said research like this is important to ensure predators like whales, seals and penguins can continue to rely on krill as their main food source.

“While current krill fishing harvests are well below the total allowable catch set by CCAMLR, demands on the fishery are expanding for products like supplements and fish meal,” Dr Welsford said.

“One of CCAMLR’s strengths is that it takes account of the needs of the ecosystem in managing its fisheries.

Australia is well recognised for its expertise in krill research which assist with the management of the krill fishery.”